THEY'RE EATING IT UP: The city's hush-hush "underground" sandwich guru drops off one of his grilled-cheese creations to a thankful customer -- part of his rapidly growing "in the know" customer base that can't get enough of his crispy, cheesy delights. Photo: Allison Joyce

(Allison Joyce)

Even though his product is available at every diner, deli and corner bodega, one New Yorker has found success selling grilled cheese on the black market.

The underground chef takes orders by text message, cooks his sandwiches on the stove in his brother’s East Village apartment, and then meets his customers on street corners. (He does have a Facebook page.)

“I feel like a drug dealer because I’m handing people a paper bag and they’re handing me cash,” the unlicensed cheese pusher, who, fearing reprisals from the Health Department, asked to be identified only as “Ronnie,” told the Post.

The sandwiches go for between $5 to $7 depending on the type of cheese and bread or the addition of extras like bacon or jalapeños.

He grills in a pan with unsalted butter, then wraps the sandwiches in tin foil and pops them into a 500-degree oven for a few minutes to achieve maximum crispiness — a trick he learned from his father.

It started with just a few friends, but now Ronnie is grilling 40 sandwiches a day, he said — a volume he can barely keep up with.

“I’m worried that I’m getting too busy. I’m instituting a friends and friends-of-friends policy,” he said. “I kind of want to quit, it’s getting too big, but I want to feed these people.”

Mostly he’s worried that if he gets too big, he’s sure to draw the attention of health inspectors.

“It’s not cool with the Department of Health,” he said. “I don’t know how much longer I want to do it because I’m living in fear. It would be such a stupid thing to get in trouble for.”

His customers said they never knew they needed a cheese dealer until they took the first bite.

“This is my lunch break. I couldn’t finish my day without one of these sandwiches,” said Lia Strassler, 26, who ordered one on wheat bread with American cheese, tomato and ground pepper.

“The sound the sandwich makes when you bite into it is incredible. There’s a crispy buttered top, and then the bread is soft and the cheese strings out. It’s better than any grilled cheese my mom ever made.”

After making that sale, Ronnie rode his bike to Broadway and Bleecker for another drop.

He met Jessica Daly, 23, who ordered jalapeño and cheddar.

“We begged for a delivery,” she recalled. “When I was in kindergarten, my dad used to make me grilled cheese every day.”

Afterward, Daly said she’d be a repeat customer.

“There’s a novelty and nostalgia to it: It comes in a paper bag and reminds me of a school lunch. It makes me think of a simpler time,” she said.